RFR: 8189685: need PerfMemory class update and a volatile_static_field support in VMStructs [v2]

[David Holmes]

On Tue, 22 Aug 2023 20:03:47 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> During [JDK-8151815](https://bugs.openjdk.org/browse/JDK-8151815) it was noted that the PerfMemory _initialized and _destroyed fields should be volatile, but VMStructs didn't have the needed support for doing that, so it was left as a future task. @YaSuenag provided a patch at the time to take care of the VMStructs support. I've integrated it, although it was far from clean due to some changes in VMStructs, and also moving OrderAccess::release_store to Atomic::release_store.
>> 
>> One other change I made to the patch had to do with consistency with using "volatile static" vs "static volatile". We already have volatile_nonstatic_field. The patch renamed static_ptr_volatile_field to static_volatile_field to make it more general purpose, but this was inconsistent with the name of volatile_nonstatic_field, so I chose the name volatile_static_field instead. This carried over into some other areas like the names of the GENERATE_VOLATILE_STATIC_VM_STRUCT_ENTRY and CHECK_VOLATILE_STATIC_VM_STRUCT_ENTRY macros.
>
> Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:
> 
>   release_store() and load_acquire() not needed for _destroyed

src/hotspot/share/runtime/perfMemory.cpp line 56:

> 54: volatile int             PerfMemory::_initialized = 0;
> 55: PerfDataPrologue*        PerfMemory::_prologue = nullptr;
> 56: volatile int             PerfMemory::_destroyed = 0;

Why was this changed to int?

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PR Review Comment: https://git.openjdk.org/jdk/pull/15373#discussion_r1302347258